Field of the Invention
The present invention generally relates to a shift control method of an electronic shift lever. More particularly, the present invention relates to a shift control method of an electronic shift lever, which prevents a further secondary collision by impeding shifting or by shifting into a parking range, when a signal for changing a shift range is generated by the movement of the electronic shift lever during a collision.
Description of Related Art
Generally, a vehicle in which an automatic transmission is mounted controls oil pressure within a shift range set according to the vehicle speed, whereby a transmission gear automatically operates to shift into a target shift range.
To perform the shifting process, the automatic transmission sets up a gear ratio using a hydraulic circuit, a planetary gear, and friction elements; and a transmission control unit (TCU) serves to control such components.
Unlike an existing mechanical shift lever, a shift-by-wire (hereinafter, referred to SBW) automatic transmission is an electronic gear shift system without a mechanical coupler between the transmission and a shift lever, such as a cable. When a lever sensor value, which is obtained by operating the electronic shift lever, is delivered to a TCU, a solenoid or an electric motor is operated by an electronic signal instructed by the TCU. Then, by the operation of the solenoid or the electric motor, oil pressure is applied to or shut off from a hydraulic circuit for each shift position, whereby the transmission may electronically perform the shift control.
Therefore, an automatic transmission based on SBW delivers a driver's intention of shifting, in a form of an electric signal, to a TCU through the simple operation of an electronic shift lever or a button. Accordingly, shifting into a driving range (D), a reverse range (R), a neutral range (N), a parking range (P), and the like is easily performed. Also, the size of the shift lever can be reduced, thus securing more space between a driver's seat and a passenger's seat.
An electronic shift lever is simple to operate but when an external force is applied, it tends to be operated against a driver's intention. Especially, by an external force from a collision, the shift lever moves regardless of the driver's intention, thus causing a signal that changes a shift range. This may lead to a secondary collision.
In other words, when a collision occurs while the shift range is in D, R, or N position, an electronic shift lever moves by inertia and may generate a signal that changes the shift range from D to R position, from R to D position, or from N to R position. In this case, because a TCU operates a transmission based on the signal of the shift lever, there may be a secondary collision with the car ahead or the car behind.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.